Organic Chemistry of Explosives

Homocubanes 77

gem-dinitro group via the oxime (67). Deprotection of the acetal (70), followed by elaboration

of the ketone functionality to agem-dinitro group, yields 8,8,11,11-tetranitropentacyclo-

[5.4.0.0^2 ,^6 .0^3 ,^10 .0^5 ,^9 ]undecane (72).

O O

O

O

O

O O

NOH

O

O

O O

O

O

Br NO 2

O O

O

O

H NO 2

O O

O

O

O 2 N

O 2 N

O 2 N

NO 2

NO 2

NO 2

NO 2

NO 2

O 2 N NO 2

O

O

O 2 N NO 2

NOH

HON

73

78 77 76

75

74

8079

NH 2 OH.HCl,

K 2 CO 3 , EtOH

79 %

NBS, dioxane

62 %

K 3 Fe(CN) 6 , NaOH

NaNO 2 , MeOH (aq)

83 %

conc. H 2 SO 4 ,

CH 2 Cl 2

50 %

NH 2 OH.HCl,

NaOAc, MeOH

75 %

1. 98 % red HNO 3 ,
   urea, NH 4 NO 3 ,
   CH 2 Cl 2 , reflux


2. 30 % H 2 O 2 (aq)
   reflux
   19 % (2 steps)

NaBH 4 ,

EtOH

84%

Figure 2.17

Marchand and co-workers^18 anticipated that aza-heterocycle formation would be a problem

for the synthesis of 4,4,8,8,11,11-hexanitropentacyclo[5.4.0.0^2 ,^6 .0^3 ,^10 .0^5 ,^9 ]undecane (80) and

so they used a similar strategy to that in figure 2.16 whereby one of the ketone groups of (73),

in either the 5- or 11-position, is protected as an acetal. A similar elaboration of the ketone

groups afforded the hexanitro derivative (80).

Chinese chemists^24 have reported the synthesis of pentacyclo[4.3.0.0^3 ,^8 ,0^4 ,^7 ]nonane-2,4-

bis(trinitroethyl ester) (88). This compound may find potential use as an energetic plastisizer

in futuristic explosive and propellant formulations. The synthesis of (88) uses widely available

hydroquinone (81) as a starting material. Thus, bromination of (81), followed by oxidation,

Diels–Alder cycloaddition with cyclopentadiene, and photochemical [2+2] cycloaddition,

yields the dione (85) as a mixture of diastereoisomers, (85a) and (85b). Favorskii rearrangement

of this mixture yields the dicarboxylic acid as a mixture of isomers, (86a) and (86b), which on

further reaction with thionyl chloride, followed by treating the resulting acid chlorides with

2,2,2-trinitroethanol, gives the energetic plastisizer (88) as a mixture of isomers, (88a) and

(88b). Improvements in the synthesis of nitroform, and hence 2,2,2-trinitroethanol, makes the

future application of this product attractive.